From: Niklas Frykholm <niklas@...>
Date: 2004-10-04T22:14:53+09:00
Subject: Re: [SOLUTION] Secret Santas (#2)

> I didn't participate, but I thought it was a trivial case of sorting the
> families by number of members and start giving santas from the most populous
> down. I should have tested that theory with code, but I didn't have time on
> the weekend :(. How can it not work?

Assume three families with one member each A, B, C. Since the families 
are the same size, sorting by size will not do anything. If we assign 
randomly, only checking that the santa is not from the same family for 
each assignment, we can get:

   A -> B
   B -> A

Now we have an impossible situation, for C cannot be his own santa.

// Niklas